Several recent NIH initiatives, including Systems and Methods for Small Animal Imaging, Small Animal Imaging Resource, and the Molecular Imaging Center programs have underscored the importance of developing laboratories with imaging capabilities that utilize small animal research models. Rats and mice, especially transgenic mice, are by the far the most widely used in vivo models for biomedical research because of certain genetic similarities to humans and the cost- effectiveness of model evaluations. Non-invasive, in vivo evaluation of anatomy, physiology and metabolism in small animals requires access to high-resolution micro-imaging devices such as microPET, microSPECT, microCT, optical scanners, and high-resolution ultrasound. Integration of these various technologies in the experimental setting are highly likely to foster rapid evaluation of proposed new drugs and treatment strategies across disease processes, as well as provide a mechanism to explore basic biological process in in vivo settings. Individually, these systems provide unique information but are limited with respect to their ability to demonstrate all aspects of anatomy or physiology; together, however, they are highly complementary. Small animal PET scanners are valuable research tools that allow investigators to image the biological process in mice the way clinicians routinely diagnose disease in patients. Despite the increasing demands in using PET, our current PET system is obsolete in its technology and cannot handle the high volume of studies we are currently facing by itself. With its obsolete technology and lower sensitivity, the imaging performance of the current system will not suffice for the growing imaging study volume and sophistication in our facility. In addition, our PET scanner is no longer supported due to its no longer being support by the vendor (Concorde). This proposal requests funding for a multimodal microPET/CT imaging system for non-invasive imaging of small animals. The requested device will be housed and operated in the Radiochemistry Facility of the Molecular Imaging Center, where it will complement other shared- use devices. The requested device will be used by investigators in the fields of medicine, surgery, pathology, neurology, biochemistry/molecular biology, dentistry, and pharmaceutical sciences. Addition of the requested instrument will increase the productivity of USC community investigators who are working in various areas of basic and translational research, enabling access to in vivo systems to evaluate fundamental biological processes. The advancements made by these investigators will ultimately have a direct positive impact on public health.